Process of wet grinding.



H. E. RIISAGER. PROCESS '0F WET GRINDING. APPLIGATION FILED APR. 1s, 1912.

1,126,085, y Patented Jan.26,1915.

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PROCESS GF WET GRINDING.

Specification of Letters atent.

Application :filed April 18, 1912. Serial No. 691,621.

To all whom it may concern.

Be it known that l, HENRIK EMIL RII- SAGER, a subject' of the King of Denmark, residing in Frederiksberg, Denmark, have invented certainnew and useful improvements in Processes of v."Vet Grinding, of which the followingis a speciicatiomreference being had to the accompanying drawing, which forms apart hereof.

in the manufacture Aof cement by the socalled wet process, in which the cement materials are ground in the presence ofl water to form a thick, creamy mass, called slurry, and in which the slurry is delivered to a ro tary kiln where the moisture is driven oi'f and the raw material is burned, it is necessary that the slurry shall have a definite and uniform consistency in order that the process may be carried on economically and with uniform results. In order that the slurry may have such definite and uniform consistency it is necessary that the quantity of water with which the material is ground in the grinding mill shall be regulated in acf cordance with the character of the material being ground and the results -to be accomplished. The proper quantity of water should be kept in the grinding mill at all times. If the water escapes too freely the material balls up in the machine, gradually closing the outlets and preventing proper operation. lf too much water is kept'in the grinding mill, the slurry is too thin or liquid and the efficiency of the plant is reduced. The mill in which the grinding of the material is carried on and this invention practised is a drum or shell which is rotated upon a horizontal aXis and to which the material to be ground and the Water are delivered at one end while the slurry is discharged at the other end. v

The object of the invention is to improve the wet process referred to above and provide a method by which it can be carried on and the proper quantity of water kept in the mill at all times, while provision is made whereby the quantity of water kept in the mill can be varied to suit different conditions.

In accordance with the invention the process is practised in a drum provided at the discharge end with a series of openings which are disposed between the center and the periphery in place of the central opening which usually surrounds the shaft of the cordance with the invention.v

drum, the grates being readily removable so that others can be substituted to vary, ac

, water retained in the drum.

` The invention will be more fully explained hereinafter with reference to the accompanying drawing in which is illustrated the preferred embodiment of apparatus for practising the improved process and in which-- Figure 1 is a view' in longitudinal section of a wet grinding drum to which the invention is applied, a portion of the feeding devices for material to be ground and for water being also indicated. Fig. 2 is a view in section on the plane indicated by the line 2-2 of Fig. l, looking in the, direction of the arrows. Fig. 3 is a detail View in elevation of one of the frames to which the grates are riveted. Fig. 4 is a detail view of the same in section. Figs 5 and 6 are similar views of one of the grates. Figs. 7 and 8 are similar views of` another grate which may be put in the place of that shown in Figs..5 and 6. Fig. 9 is a detail View of a closure which may be put in place of any of the grates. Fig. l() is a fragmentary View in section showingy a portion of the head of the drum and showing the application there to of a frame and grate constructed in ac- Except With respect to the openings through which the slurry is dischargedthe mill may be of any usual or suitable construction. As shown it comprises a cylindrical drum @,provided with a suitable lining b, and mounted through its feed head V0 and discharge head al upon a shaft e which is mounted torotate'in suitable bearings not shown. The feed head c has a central `feed opening f through which the material to bef ground is delivered through a feed chute indicated at g, the water being supplied to the feed chute through a pipe h. The discharge head d is provided, between the center and the periphery, and preferably nearer the periphery than the center, with openings z' Awhich are preferably arranged symmetrically. To the head d, about each opening a', is riveted a frame la, provided in its edge with under cut slots k tof'rec'eive the heads of bolts Z by which thegrate frame m is removably secured in place, the latter frame being also provided in its edge with slots m Patented dan.. 26:3, Elfl.,

los

for the bolts Z.` llfhe grate a or a or the 31o closure a2 is preferably riveted vto the frame m and, as shown, in the drawing each grate is provided with openings n3 which flare outwardly so as to prevent the clogging of the openings by the slurry. The grate n is provided with openings over its whole available area and grates of this kind are intended to be used when the quantity. of water to be kept in the drum is minimum. The grate n `shown in Figs. 7 and 8, has openings n3 only in that portion which lies nearest the axis of the drum and is intended to be used, in place of the grate n, when a-larger quantity of water is to be retained in the drum.

' A complete closure n2, shown in Fig. 9, may

be substituted for one or more of the grates if it is desired to reduce still further the escape of Water from the drum. It will be understood that each grate preferably has its own frame and can be substituted quickly for any other grate. Obviously the grates miht be formed integral with the frames m, ut for convenience in manufacture they are formed separately therefrom and are riveted thereto.'

The operation of Wet grinding is carried on with the improved mill substantially as in an ordinary mill, but it will be seen that by disposing the discharge openings between the center of the drum and the periphery the slurry can escape only when it has accumulated in the drum to a height above the lowest point of the frame equal to the distance of the nearest opening n3 in'the lowermost grate n from such point, whereby the desired quantity of Water is retained in the frame. By making the grates interchangeable, as shown, it becomes possible to regulate the escape of the slurry and the quantity of water retained in the drum and it is with the improved method of regulating the quantity of water and the consistency of the slurry that this invention is concerned.

I claim as my nventionz- The improvement in the manufacture of cement by the wet process, which consists in placing the cement materials with water in a rotary drum to form slurry, regulating the consistency of the slurry by varying the effective radial distance of the openings in the discharge head of the drum through which the water and the slurry escape from the drum, and thereafter driving olf the moisture from the slurry and burning the residue.

This specification. signed and witnessed thisQnd day of April A. D., 1912.

HENRIK RIISAGER. Signed in the presence o f- CHR. ENGELHART, VILH. OTzEN. 

